Method for marking liquid petroleum hydrocarbons

ABSTRACT

A method for marking a liquid petroleum hydrocarbon; said method comprising adding to said liquid petroleum hydrocarbon at least one dye having an unsaturated cyclic nucleus comprising at least nine ring atoms, and having at least one (CN) 2 C═ substituent and at least one Ar—N═ substituent; wherein Ar is a substituted aryl group.

[0001] This invention relates generally to a method for marking apetroleum hydrocarbon with at least one dye for subsequentidentification.

[0002] Dyes containing (CN)₂C═ and Ar—N═ substituents on an unsaturatedcyclic nucleus are disclosed in K. A. Bello et al., J. Chem. Soc. PerkinTrans. II, 1987, pp. 815-818. This reference, however, does not suggesta method for marking petroleum hydrocarbons.

[0003] The problem addressed by this invention is to find additionalcompounds having an absorption maximum of at least 600 nm which areuseful for marking petroleum hydrocarbons.

STATEMENT OF THE INVENTION

[0004] This invention is directed to a method for marking a liquidpetroleum hydrocarbon; said method comprising adding to said liquidpetroleum hydrocarbon at least one dye having an unsaturated cyclicnucleus comprising at least nine ring atoms, and having at least one(CN)₂C═ substituent and at least one Ar—N═ substituent; wherein Ar is asubstituted aryl group.

DETAILED DESCRIPTION OF THE INVENTION

[0005] All percentages are weight percentages, unless otherwiseindicated. Concentrations in parts per million (“ppm”) are calculated ona weight/volume basis. The term “petroleum hydrocarbons” refers toproducts having a predominantly hydrocarbon composition, although theymay contain minor amounts of oxygen, nitrogen, sulfur or phosphorus,that are derived from petroleum refining processes, preferablylubricating oil, hydraulic fluid, brake fluid, gasoline, diesel fuel,kerosene, jet fuel and heating oil. An “alkyl” group is a hydrocarbylgroup having from one to twenty carbon atoms in a linear, branched orcyclic arrangement. Alkyl groups optionally have one or more double ortriple bonds. Substitution on alkyl groups of one or more halo, cyano,hydroxy, alkoxy, alkanoyl or aroyl groups is permitted. Preferably,alkyl groups have no halo or alkoxy substituents. An “alkoxy” group isan alkyl group linked via an oxygen atom, i.e., a hydroxy groupsubstituted by an alkyl group. A “heteroalkyl” group is an alkyl grouphaving at least one carbon which has been replaced by O, NR, or S,wherein R is hydrogen, alkyl, heteroalkyl, aryl or aralkyl. An “aryl”group is a substituent derived from an aromatic hydrocarbon compound. Anaryl group has a total of from six to twenty ring atoms, and has one ormore rings which are separate or fused. An “aralkyl” group is an “alkyl”group substituted by an “aryl” group. A “heterocyclic” group is asubstituent derived from a heterocyclic compound having from five totwenty ring atoms, at least one of which is nitrogen, oxygen or sulfur.Preferably, heterocyclic groups do not contain sulfur. A substitutedaryl or substituted heterocyclic group has one or more substituentsselected from halo, hydroxy, amino, cyano, nitro and organic functionalgroups; preferably, substitution on aryl or heterocyclic groups islimited to amino, alkylamino, dialkylamino, alkanoylamino, halo, cyano,nitro, hydroxy, alkyl, heteroalkyl, alkanoyl, aroyl or alkoxy groups.Preferably, aryl and heterocyclic groups do not contain halogen atoms.An “aromatic heterocyclic” group is a heterocyclic group derived from anaromatic heterocyclic compound.

[0006] An “organic functional group” is a functional group which doesnot contain metal atoms, and which has from one to twenty-two carbonatoms, hydrogen atoms, and optionally heteroatoms, including but notlimited to: nitrogen, oxygen, sulfur, phosphorus, silicon and halogenatoms. An organic functional group optionally contains double and/ortriple bonds; rings, which are linked or fused; and if the group iswholly or partly acyclic, the acyclic part can be linear or branched.

[0007] Preferably, the substituted aryl group, Ar, of the Ar—N═substituent is substituted phenyl, substituted naphthyl, substitutedanthracenyl, substituted benzofuranyl or substituted benzopyrrolyl. Morepreferably, the aryl group is substituted phenyl or substitutednaphthyl. Preferably, the substituents on the substituted phenyl orsubstituted naphthyl group are selected from amino, hydroxy and organicfunctional groups. Most preferably, the aryl group is substitutedphenyl, and the Ar—N═ substituent has formula (I)

[0008] wherein X is amino, substituted amino, hydroxy or alkoxy; and R¹,R², R³ and R⁴ independently are selected from hydrogen, amino, hydroxy,halo and organic functional groups. Substituted amino groups are aminogroups in which one or both hydrogen atoms have been replaced by alkyl,alkanoyl, aryl or aralkyl groups; when both hydrogen atoms have beenreplaced, the groups are selected independently. Preferably, R¹, R², R³and R⁴ independently are selected from hydrogen, alkyl, amino,substituted amino, hydroxy and alkoxy. Most preferably, X is NR¹⁴R¹⁵,wherein R¹⁴ and R¹⁵ independently are hydrogen or alkyl. Morepreferably, at least one of R¹⁴ and R¹⁵ is alkyl, and most preferablyboth of R¹⁴ and R¹⁵ are alkyl. Preferably, R¹⁴ and R¹⁵ independently areselected from among the C₄-C₂₀ alkyl groups. In one preferred embodimentof the invention, R¹ and R³ are hydrogen and at least one of R² and R⁴is amino, substituted amino, hydroxy or alkoxy. In another preferredembodiment, R¹, R², R³ and R⁴ are hydrogen.

[0009] Preferably, the unsaturated cyclic nucleus has from nine tofourteen ring atoms. More preferably, the unsaturated cyclic nucleus isselected from among

[0010] wherein Y is CH₂, NR¹³ or O; and R⁵, R⁶, R⁷, R⁸, R⁹, R¹⁰, R¹¹,R¹² and R¹³ independently are selected from hydrogen, halo, cyano, nitroand organic functional groups. Preferably, R⁵, R⁶, R⁷, R⁸, R⁹, R¹⁰, R¹¹,R¹² and R¹³ independently are hydrogen, alkyl, halo, cyano or nitro. The(CN)₂C═ substituent(s) and substituent(s) of formula (I) are attached toany saturated carbon in the cyclic nuclei depicted above. Preferably, Yis CH₂. Preferably, the cyclic unsaturated nucleus has nine or ten ringcarbon atoms and, with (CN)₂C═ and Ar—N═ substituents attached,comprises an aromatic ring system.

[0011] Preferably, each dye according to this invention is selected fromamong

[0012] wherein Z represents O or C(CN)₂. Preferably, in the secondstructure above, Z represents C(CN)₂, giving this dye the followingstructure (VII)

[0013] Preferably, R⁵, R⁶, R⁷, R⁸, R⁹, R¹⁰, R¹¹ and R¹² independentlyare hydrogen or alkyl. Most preferably, R⁵, R⁶, R⁷, R⁸, R⁹, R¹⁰, R¹¹ andR¹² are hydrogen.

[0014] Preferably the amount of each dye which is added to the petroleumhydrocarbon is at least 0.01 ppm, more preferably at least 0.02 ppm, andmost preferably at least 0.03 ppm. Preferably the amount of each dye isless than 10 ppm, more preferably less than 2 ppm, and most preferablyless than 1 ppm. Preferably, the marking is invisible, i.e., the dyecannot be detected by simple visual observation of the markedhydrocarbon. Preferably, a dye used in the method of this invention,having an unsaturated cyclic nucleus comprising at least nine ringatoms, and having at least one (CN)₂C═ substituent and at least oneAr—N═ substituent, has an absorption maximum in the range from 600 nm to1000 nm. Preferably, it has an absorption maximum at a wavelength of atleast 650 nm, more preferably at least 700 nm, more preferably at least720 nm and most preferably at least 750 nm; preferably, the absorptionmaximum is no greater than 900 nm, more preferably no greater than 875nm. In one embodiment, at least two dyes according to the method of thisinvention, and having absorption maxima at differential wavelengths areadded to the petroleum hydrocarbon. In another embodiment, at least onedye according to the method of this invention and at least one other dyehaving an absorption maximum in the range from 600 nm to 1000 nm,preferably from 700 nm to 1000 nm, are added to the petroleumhydrocarbon. Preferably, each of the other dyes absorbing in this rangeis present in an amount of at least 0.01 ppm, more preferably at least0.02 ppm, and most preferably at least 0.03 ppm. Preferably the amountof each other dye is less than 10 ppm, more preferably less than 2 ppm,and most preferably less than 1 ppm.

[0015] Preferably, a dye used in the method of this invention isdetected by exposing the marked petroleum hydrocarbon to electromagneticradiation having wavelengths in the portion of the spectrum containingthe absorption maxima of the dye and detecting the absorption of lightor fluorescent emissions. It is preferred that the detection equipmentis capable of calculating dye concentrations and concentration ratios ina marked petroleum hydrocarbon. Typical spectrophotometers known in theart are capable of detecting the dyes used in the method of thisinvention when they are present at a level of at least 0.01 ppm. It ispreferred to use the detectors described in U.S. Pat. No. 5,225,679,especially the SpecTrace™ analyzer available from Rohm and Haas Company,Philadelphia, Pa. These analyzers use a filter selected based on theabsorption spectrum of the dye, and use chemometric analysis of thesignal by multiple linear regression methods to reduce thesignal-to-noise ratio.

[0016] When the detection method does not involve performing anychemical manipulation of the marked petroleum hydrocarbon, the samplemay be returned to its source after testing, eliminating the need forhandling and disposal of hazardous chemicals. This is the case, forexample, when the dyes are detected simply by measuring light absorptionor fluorescence of a sample of the marked petroleum hydrocarbon.

[0017] In one embodiment of the invention, the dye is formulated in asolvent to facilitate its addition to the liquid petroleum hydrocarbon.The preferred solvents for the dyes are aromatic hydrocarbon solvents.Preferably, the dye is present in the solvent at a concentration of from0.1% to 10%.

[0018] In one embodiment of the invention, at least one dye having anunsaturated cyclic nucleus comprising at least nine ring atoms, andhaving at least one (CN)₂C═ substituent and at least one Ar—N═substituent, and having an absorption maximum from 700 nm to 1000 nm,and optionally another dye having an absorption maximum from 700 nm to1000 nm, are added to a petroleum hydrocarbon with at least one visibledye; i.e., a dye having an absorption maximum in the range from 500 nmto 700 nm, preferably from 550 nm to 700 nm, and most preferably from550 nm to 680 nm. Preferably, each visible dye is added in an amount ofat least 0.1 ppm, preferably at least 0.2 ppm, and most preferably atleast 0.5 ppm. Preferably, the amount of each visible dye is no morethan 10 ppm, more preferably no more than 5 ppm, more preferably no morethan 3 ppm, and most preferably no more than 2 ppm. In a preferredembodiment, the visible dyes are selected from the classes ofanthraquinone dyes and azo dyes. Suitable anthraquinone dyes having anabsorption maximum in this region include, for example,1,4-disubstituted anthraquinones having alkylamino, arylamino oraromatic-heterocyclic-amino substituents. Suitable azo dyes having anabsorption maximum in this region include the bisazo dyes, for example,those having the structure Ar—N═N—Ar—N═N—Ar, in which Ar is an arylgroup, and each Ar may be different. Specific examples of suitablecommercial anthraquinone and bisazo dyes having an absorption maximum inthis region are listed in the Colour Index, including C.I. Solvent Blue98, C.I. Solvent Blue 79, C.I. Solvent Blue 99 and C.I. Solvent Blue100.

[0019] Incorporation of at least one dye having an unsaturated cyclicnucleus comprising at least nine ring atoms, and having at least one(CN)₂C═ substituent and at least one Ar—N═ substituent, and having anabsorption maximum in the region from 600 nm to 1000 nm allowsidentification of the liquid hydrocarbon by spectrophotometric means ina spectral region relatively free of interference. Low levels of thesedyes are detectable in this region, allowing for a cost-effectivemarking process, and availability of multiple dyes allows coding ofinformation via the amounts and ratios of the dyes. For these reasons,additional compounds absorbing in this range, and suitable as fuelmarkers, are extremely useful.

[0020] Combinations of markers detectable at 700 nm to 1000 nm withmarkers detectable in the visible range also are useful. Incorporationof higher levels of at least one visible dye having an absorptionmaximum in the region from 500 nm to 700 nm facilitates quantitativespectrophotometric determination in this region. Accurate determinationof the dye levels allows the amounts and ratios of the dyes to serve asparts of a code identifying the hydrocarbon. Since dyes absorbing inthis region often are less costly, use of a higher level will notgreatly increase the overall cost of the marking process. Thus, thecombination of the two kinds of dyes increases the flexibility andminimizes the cost of the marking process.

1. A method for marking a liquid petroleum hydrocarbon; said methodcomprising adding to said liquid petroleum hydrocarbon at least one dyehaving an unsaturated cyclic nucleus comprising at least nine ringatoms, and having at least one (CN)₂C═ substituent and at least oneAr—N═ substituent; wherein Ar is a substituted aryl group.
 2. The methodof claim 1 in which the unsaturated cyclic nucleus is selected fromamong

wherein Y is CH₂, NR¹³ or O; and R⁵, R⁶, R⁷, R⁸, R⁹, R¹⁰, R¹¹, R¹² andR¹³ independently are selected from hydrogen, halo, cyano, nitro andorganic functional groups.
 3. The method of claim 2 in which the Ar—N═substituent has formula

wherein X is amino, substituted amino, hydroxy or alkoxy; and R¹, R², R³and R⁴ independently are selected from hydrogen, amino, hydroxy, haloand organic functional groups.
 4. The method of claim 3 in which said atleast one dye is selected from among

wherein Z represents O or C(CN)₂.
 5. The method of claim 4 in which R¹,R², R³, R⁴ independently are hydrogen, alkyl, halo, amino, substitutedamino, hydroxy or alkoxy; R⁵, R⁶, R⁷, R⁸, R⁹, R¹⁰, R¹¹ and R¹²independently are hydrogen, alkyl, halo, cyano or nitro; and X isNR¹⁴R¹⁵, wherein R¹⁴ and R¹⁵ independently are hydrogen or alkyl.
 6. Themethod of claim 5 in which Z represents C(CN)₂; R¹ and R³ are hydrogen;and R⁵, R⁶, R⁷, R⁸, R⁹, R¹⁰, R¹¹ and R¹² independently are hydrogen oralkyl.
 7. The method of claim 1 in which said at least one dye has anabsorption maximum in the range from 600 nm to 1000 nm.
 8. The method ofclaim 7 in which each dye is present in an amount from 0.01 ppm to 2 ppmand has an absorption maximum from 700 nm to 1000 nm.
 9. The method ofclaim 8 further comprising at least one dye having an absorption maximumfrom 500 nm to 700 nm.
 10. The method of claim 8 in which at least twodyes are present, each of which has an absorption maximum from 700 nm to1000 nm.